JP2704580B2 - Manufacturing method of metal fiber sintered sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal fiber used for a filter material, a heat-resistant material, and the like. The present invention relates to a method for producing a fiber sintered sheet.

[0002]

2. Description of the Related Art It is known that foreign substances can be trapped efficiently by using filters having different average pore diameters (hereinafter, referred to as pore diameters) in a laminating manner so that the pore diameters gradually decrease in the direction of fluid flow. Have been. From such a background, the following sheets have conventionally been proposed. That is, as a method for producing a metal fiber sintered sheet having a pore diameter having a tilt structure in the thickness direction, a metal mesh having different fiber diameters, a web, a woven fabric is laminated, or a metal powder having a different particle diameter, and a short fiber are used. By spraying on a binder, the layers are laminated to form a laminated body. Thereafter, these laminated bodies are pressurized in a vacuum or in an inert gas, heated and sintered to fuse the metal fibers. A method for causing this to occur is known.

[0003] However, according to the above-mentioned prior art, although a tilted structure of the hole diameter can be obtained, a thin sheet cannot be obtained when laminating a wire mesh, web, or woven fabric manufactured by braiding or weaving. Can't do something small. Also,
Particle size, powder of different fiber diameter, the method of spraying and laminating short fibers, the powder in the sheet by spraying, there is a large variation in the amount of single fiber sprayed, causing the problem that thick and thin spots occur on the obtained sheet, Further, there is a problem that a long product cannot be formed.

On the other hand, the present applicant has filed Japanese Patent Application No. Hei.
8 proposed a method of laminating and sintering the metal fiber high blended sheet made by the wet papermaking method by heating and pressing, and the metal fiber sintered sheet obtained by the manufacturing method is capable of forming a thin leaf sheet and Although it was possible to prepare a sheet having a small hole diameter, it was impossible to form a sheet having a small hole diameter. In addition, there was a problem that sintering, insufficient reduction, wrinkles, swelling, peeling, and the like occurred.

[0005]

SUMMARY OF THE INVENTION The present inventor has devised to solve the above-mentioned problems, and as a result, after laminating metal fiber sheets having different fiber diameters which have been preliminarily sintered, re-sintering is performed. The distribution of pore diameters in the thickness direction of the sheet is arbitrarily controlled in an inclined structure or the like, and a thin, uniform sheet is obtained without sintering, insufficient reduction, wrinkles, swelling, spots, etc. Manufacturing method is provided.

[0006]

According to the present invention, there is provided (A) a step of forming a plurality of metal fiber sheets having different fiber diameters from each other by forming a slurry of fibers containing metal fibers as a main component into sheets by a wet papermaking method. (B) sintering the metal fiber sheet to form a plurality of single-layer sintered sheets of metal fibers;
(C) a step of arbitrarily laminating the single-layer sintered sheets to form a laminated body, and (D) a step of sintering the laminated body. An object of the present invention is to provide a method for manufacturing a binding sheet.

Hereinafter, an example of the method for producing a metal fiber sintered sheet of the present invention will be described in detail. First, three metal fiber sheets having a fiber diameter A>B> C are prepared by a wet papermaking method. That is, a slurry in which the blending ratio of the metal fibers (fiber diameter A) is adjusted to 70% by weight or more is formed by a wet papermaking method, dehydrated and heated and dried to prepare a metal fiber sheet A ′ having a fiber diameter A. In the case of wet papermaking, as a binder fiber to be blended, for example, Kuraray Co., Ltd. Kuraray Vinylon Fibribond VPB105-1-3
70 ° C. solubility in water, known as (trade name)
Is easily used. In the same manner, a metal fiber highly blended sheet B ′ having a fiber diameter B smaller than the fiber diameter A and a metal fiber sheet C ′ having a fiber diameter C smaller than the fiber diameter B are produced in the same manner.

The metal fiber sheets A'B 'and C' are mixed with metal fibers having a fiber diameter other than A, B and C within the range of A>B> C in average fiber diameter. May be. Further, different materials may be used for the metal fibers.

Next, the metal fiber sheets A ', B' and C 'obtained in this manner are heated under a dry hydrogen gas atmosphere to reduce the melting point of the metal fibers in order to prevent the surface of the metal fibers from being oxidized and to reduce the effects. Single-layer sintered sheets A ", B" and C "of metal fibers which have been subjected to degreasing and sintering at temperatures not exceeding, respectively, are prepared. About 12 for stainless steel fiber
Sintering is performed in a continuous furnace at a sintering speed of 15 to 20 cm / min by setting 00 ° C. as a sintering temperature. In this case, the sintering is performed in a continuous hydrogen furnace, and also in a continuous sintering furnace using an inert gas atmosphere furnace with an inert gas atmosphere furnace such as nitrogen gas as a pre-process and a hydrogen gas atmosphere furnace as a post-process. You may.

Thereafter, the single-layer sintered sheets A ", B" and C "of metal fibers having different fiber diameters obtained by the above-mentioned method are made to have a distribution of pore diameters in a target thickness direction. Then, for example, a laminate is formed by laminating in the order of A "/ B" / C "to form a laminate, and sintering is performed between the laminates under the same sintering conditions as described above. Obtain a knot sheet. The single-layer sintered sheets of metal fibers having different fiber diameters may be laminated in multiple layers of three or more according to the purpose of use, and the order of lamination is not limited to the above-described inclined structure. In consideration of the proportional relationship between the diameter and the hole diameter, the layers can be arbitrarily laminated in order to obtain a necessary distribution of the hole diameter in the thickness direction.

In the present invention, in the process of heating at the time of primary sintering in a continuous sintering furnace, first, when the nonmetallic fiber as the binder in the metal fiber sheet is PVA fiber, it is thermally decomposed at about 400 ° C. As a result, once the entanglement between the fibers is lost and the handling of the sheet is also lost, but when the temperature is further increased, for example, to about 800 ° C. in the case of stainless steel fiber, a part of the metal fiber starts to sinter, and the inter-fiber bonding occurs, and A sheet having high physical strength can be obtained. Further, in order to further stabilize the bonding, the entangled state, and the pore size between the metal fibers, a pressure treatment may be performed after or at the time of sintering. However, the pressure treatment may not be performed depending on the purpose of use.

The metal fibers used in the present invention have a fiber diameter of 1 to 50 μm, preferably 1 to 20 μm, and a fiber length of 0.5 to 12 mm, preferably 2 to 6 mm. And a metal fiber such as aluminum. Among them, stainless steel fiber is particularly preferably used because fine wire processing is possible, heat resistance and rust resistance are good. When the fiber diameter is 1 μm or less, the strength of the metal fiber is too low to make papermaking, and when the fiber diameter is 50 μm or more, the metal fiber sticks to the blanket and hinders papermaking. Further, if the fiber length is 0.5 mm or less, it becomes difficult to entangle between the metal fibers, and if the fiber length is 12 mm or more, the metal fibers become a lump,
Causes inconvenience.

[0013]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. Example 1. From 90 parts by weight of stainless steel fiber (SUS316L) having a fiber diameter of 8 µm (fiber diameter A) and a fiber length of 4 mm, and 10 parts by weight of PVA fiber (Fibribond VPB105-1-3 manufactured by Kuraray Co., Ltd.) having a solubility in water of 70 ° C. The resulting slurry was formed into a sheet by a wet papermaking method, and then dehydrated and dried by heating to obtain a metal fiber sheet A ′ having a rice basis weight of 110 g / m ² .
Next, using a stainless fiber (SUS316L) having a fiber diameter of 4 μm (fiber diameter B) and a fiber length of 4 mm, a metal fiber sheet B ′ was obtained in the same manner as described above. Same fiber diameter 2μ
m (fiber diameter C), stainless steel fiber with a fiber length of 3 mm (SU
S316L) to obtain a metal fiber sheet C ′ in the same manner. Then, the metal fiber sheets A′B ′ and C ′ were sintered using a hydrogen gas continuous sintering furnace at a sintering temperature of 1120.
Sintering was performed at a temperature of 15 ° C. and a speed of 15 cm / min to produce single-layer sintered sheets A ″, B ″ and C ″ of metal fibers.
A single-layer sintered sheet of metal fiber is laminated in the order of A "/ B" / C "to form a laminate, and again using a hydrogen gas continuous sintering furnace at a sintering temperature of 1120 ° C. and a speed of 15 cm / min. Further, the sheet was subjected to a sintering process to stabilize the entangled state between fibers and the average pore diameter.
^2. Pressurizing at 3m / min speed, fiber diameter A> B
A sintered metal fiber sheet of the present invention having a tilted structure with a pore diameter corresponding to the relationship of> C was obtained.

Example 2 Fiber diameter 8 μm (fiber diameter A1)
45 parts by weight of stainless steel fiber with 4 mm fiber length, fiber diameter 4μ
m (fiber diameter A2), stainless steel fiber 45 with a fiber length of 4 mm
A metal fiber sheet A 'was obtained from a slurry comprising 10 parts by weight of PVA fiber having a solubility in water of 70 ° C in the same manner as in the example. Next, a fiber diameter of 8 μm (fiber diameter B1), 45 parts by weight of stainless steel fiber having a fiber length of 4 mm, and a fiber diameter of 2 μm
(Fiber diameter B2) A metal fiber sheet B 'was prepared from a slurry composed of 45 parts by weight of stainless steel fibers having a fiber length of 3 mm and 10 parts by weight of PVA fibers in the same manner as described above. Next, the metal fiber sheets A 'and B' were sintered in the same manner as in Example 1 to obtain single-layer sintered sheets A 'and B' of metal fibers. The single-layer sintered sheets A ″ and B ″ of the obtained metal fibers were laminated to form a laminate, and sintering was again performed under the same sintering conditions as described above. Further, the sheet was subjected to a pressure treatment under the same conditions as in Example 1 and the fiber diameter was A1 + A2> B
A sintered metal fiber sheet of the present invention having a tilted structure with a hole diameter corresponding to the relationship of 1 + B2 was obtained.

Comparative Example 1. The metal fiber sheets A ', B' and C 'obtained in Example 1 were laminated without going through the step of preparing a single-layer sintered sheet of metal fibers, and the roll temperature was 1
Thermocompression bonding was performed at 70 ° C., a linear pressure of 300 kg / cm ² , and a speed of 3 m / min.

The average value of the pore diameter of each layer of the sintered metal fiber sheet obtained in Examples 1 and 2 was determined using a palm porometer (PMI).
Are shown in Table 1. 1 and 2
2 shows a cross-sectional photograph (500-fold magnification) of the metal fiber sintered sheets obtained in Examples 1 and 2 by a scanning electron microscope. As is clear from these figures, it can be seen that the lamination has an inclined structure and a thin sheet is obtained. On the other hand, the sintered metal fiber sheet of Comparative Example 1 obtained by sintering under the same conditions as in Example 1 was expanded and peeled due to sintering, insufficient reduction, and the difference in thermal shrinkage between the respective layers. In addition, spots and the like occurred, and a sintered metal fiber sheet having a structure in which the hole diameter was inclined could not be formed.

[0017]

[Table 1]

[0018]

According to the production method of the present invention, the hole diameter can be arbitrarily controlled in the sheet thickness direction in an inclined structure or the like, and the thin and long sheet having no swelling, peeling, spots, etc. which cannot be obtained by the prior art. A metal fiber sintered sheet can be obtained. In addition, the properties of the metal fiber itself, particularly strength, heat resistance, without impairing the conductivity of the sheet-like material without impairing its function,
In addition, since the strength between fibers is sufficient, it can be applied to many industrial uses such as filters.

[Brief description of the drawings]

FIG. 1 is a cross-sectional photograph of a sintered metal fiber sheet of Example 1 taken by a scanning electron microscope.

FIG. 2 is a cross-sectional photograph of a sintered metal fiber sheet of Example 2 taken by a scanning electron microscope.

Claims (2)

(57) [Claims] (A) a step of forming a plurality of metal fiber sheets having different fiber diameters from each other by forming a slurry of fibers mainly composed of metal fibers into a sheet by a wet papermaking method;
(B) sintering the metal fiber sheet to form a plurality of single-layer sintered sheets of metal fibers; and (C) arbitrarily laminating the single-layer sintered sheets to form a laminate. And (D) a step of sintering the laminate. 2. The metal fiber has a fiber diameter of 1 to 50 μm and a fiber length of 0.5 to 12 mm.
The method for producing a metal fiber sintered sheet according to the above.